Approximately 1.6 million Americans live in the nation's 16,000 nursing homes (NHs) and the frail elderly account for 90% of the residents. This population is expected to increase dramatically and become more diverse in the coming years. It is reported that between 1.6 and 3.8 million infections occur each year in U.S. NHs. Healthcare associated infections (HAI) are leading causes of morbidity and mortality among residents and this vulnerable population is considered high risk for infection and colonization with multi-drug resistant organisms (MDRO). We have found that 15% of U.S. NHs receives deficiency citations for infection control each year indicating a clear need to focus on prevention in these settings. In NHs there is little research documenting the efficacy of infection control related structures or processes in preventing HAI. Some states have regulated mandatory reporting of HAI in NHs and other states have implemented statewide learning collaborative; however, the effectiveness of these initiatives is not known. Research is clearly needed to understand best practices related to HAI prevention and the value of infection control in this setting. Building upon our previous work in acute care and partnering with experts conducting research in NHs, we propose a 4- year, mixed-method, comparative effectiveness study that will address these gaps. Our aims are: 1) Describe the incidence of HAI (pneumonia, sepsis, urinary tract infections, wound infections and MDRO infections/colonization) in NHs across the nation and associated state level characteristics (e.g., mandatory reporting and statewide collaborative), facility level characteristics (e.g., ownership, bed size and nurse staffing) and resident care processes (e.g., isolation); 2) Identify NHs that have persistently high and low HAI rates and the relationship between the HAI rates, state and facility level characteristics and resident care processes; 3) Use a descriptive exploratory approach to describe the phenomenon of infection control in NHs; 4) Determine the comparative effectiveness of current infection control structures and processes in preventing HAIs in elderly residents; and 5) Determine the cost-effectiveness of efficacious infection control processes in NHs. The analytic strategy for Aim 3 includes well-developed qualitative procedures that maximize completeness and truthfulness of the data. The analytic strategies for Aims 1, 2, 4 and 5 include state of the art multivariate econometric methods designed to minimize potential bias and address clustering of data. Our interdisciplinary team is uniquely qualified to conduct this study. Results will inform bedside clinicians and policy makers across the nation on how to best eliminate HAIs in NHs and inform future guidelines.